There exist many types of computer device where the display is controlled by an input. In some embodiments the input may be a cursor or pointer that is controlled by a human interface device such as a mouse, joystick, keyboard etc. Additionally or alternatively the display may comprise a touchscreen which can be controlled by a user's touch. That is, activation of functions and objects is responsive to user input made by way of the user actually touching a particular object displayed on the screen, and thereby selecting that object. Most commonly, that touch is by a user's finger.
There are many technical challenges and technical considerations facing the designer of computer applications such as games executed on a user or computer or other device having a user interface, such as designing algorithms for controlling the game mechanic.
One particular context is that of a computer game where a game board is displayed to a user which has adjacent selectable objects, for example in the form of game tiles having at least one characteristic, displayed in an arrangement. In one game, the mechanic of the game is that a user should select a tile and switch it with an adjacent tile to form a sequence of three or more game tiles having matching characteristics.